An Organic Sacrificial Salt with Low Decomposition Potential Driven by Substituent Effect Enables High‐Performance Lithium‐Ion Batteries

The irreversible Li⁺ loss during solid electrolyte interphase (SEI) formation significantly critically constrains the energy density of lithium-ion batteries (LIBs). To address this issue, we rationally design lithium N,N-dimethylglycinate (Li-DMG) as an organic sacrificial salt (OSS) via substituent effect engineering, achieving a low decomposition potential (3.58 V versus Li⁺/Li). Li-DMG delivers a near-theoretical capacity (238.2 mAh g^-1, 96% efficiency) during initial charging. Incorporated into LiFePO₄ (LFP) cathodes, Li-DMG/LFP||graphite full cells exhibit 17.3% higher initial discharge capacity (114.4 versus 97.5 mAh g^-1) and 43.1% enhanced capacity retention after 200 cycles (67.1 versus 46.9 mAh g^-1) compared to LFP||graphite full cells. Besides, Li-DMG promotes the formation of SEI layer rich in more inorganic component, e.g., LiF, suppressing the degradation of electrolyte solvents and electrode structures. Furthermore, pouch-type LIBs containing Li-DMG demonstrate a prominent enhancement in the specific capacity (114.4 versus 87.1 mAh g^-1) and cycle stability (59.0 mAh g^-1 after 5000 cycles versus 45.4 mAh g^-1 after 500 cycles). This study provides a promising strategy for improving the energy density and cycle stability of LIBs through the use of OSSs with low decomposition potentials.